[1] On Gibbs see George Gibbs, The Gibbs Family of Rhode Island and Some Related Families, New York, 1933, 18-21, Dictionary of American Biography, 20 vols., New York, 1928-1936, reprinted in 10 vols. with 8 supplements, New York, 1944-1988, 4 (part 1):244-245, and Stephen Dow Beckham, "Colonel George Gibbs," In Benjamin Silliman and his Circle: Studies on The Influence of Benjamin Silliman on Science in America, edited by Leonard G. Wilson, New York, 1979, 28-47. Tom Michie's research on these portraits (NGA curatorial files) has been very helpful in writing these entries.

[2] For her dates see Gibbs 1933, 21-25.

[3] Lazarus acted as the Gibbs' agent in the sale. After agreeing upon the price, he wrote Coolidge on 27 June 1872 that he was sending the portraits to Boston the next day with some documents concerning their history. These were his copies of letters written to Mrs. Gibbs in the 1850s certifying that the portraits were painted by Stuart for Colonel Gibbs (copies, NGA curatorial files). On Coolidge see Dictionary of American Biography, 2 (part 2):395, and Emma Downing Coolidge, Descendants of John and Mary Coolidge of Watertown, Massachusetts, Boston, 1930, 351.

[4] Coolidge 1930, 353; his father Thomas Jefferson Coolidge II died in 1912.